Physicists detect a new type of molecular bond with an unusual bond length of several micrometers

Amazing stuff! At thefrontier of ultracold chemistry and physics!

"... Using a specially designed microscope, the team observed a binding mechanism between a charged ion and a neutral Rydberg atom ... The extent of the bond length in the new molecule is as wide as a few micrometres, which is at least 1000 times larger than in usual molecules. ...
To verify the molecule’s formation, the researchers devised a special ion microscope. ... in this microscope an electric field separates the molecule and ionizes the Rydberg atom. The now separated ion and Rydberg core are then guided along the microscope and onto a detector. Due to their different charge-mass ratios, the Rydberg core and the ion will arrive at this detector at different times, allowing each of them to be detected individually. ..."

"Ultracold temperatures in atomic and molecular gases have allowed for a new branch of chemistry, where novel weak binding mechanisms between atoms have been observed. ..."

From the abstract:

"Atoms with a highly excited electron, called Rydberg atoms, can form unusual types of molecular bonds. The bonds differ from the well-known ionic and covalent bonds not only by their binding mechanisms, but also by their bond lengths ranging up to several micrometres. Here we observe a new type of molecular ion based on the interaction between the ionic charge and a flipping-induced dipole of a Rydberg atom with a bond length of several micrometres. We measure the vibrational spectrum and spatially resolve the bond length and the angular alignment of the molecule using a high-resolution ion microscope. As a consequence of the large bond length, the molecular dynamics is extremely slow. These results pave the way for future studies of spatio-temporal effects in molecular dynamics (for example, beyond Born–Oppenheimer physics)."

Physicists detect a new type of molecular bond – Physics World

Observation of a molecular bond between ions and Rydberg atoms (no public access)

Spatial imaging of a novel type of molecular ions (corresponding preprint article)